The present invention relates to a sheet finishing apparatus which receives sheets delivered from an image forming apparatus or the like, and reverses the sheets by a reversing means.
Conventionally, in the case where a sheet (hereinafter, also called a recording sheet) on which an image has been formed by an image forming apparatus such as a copier, printer, or the like, is successively delivered and stacked with an image facing upward, initially the first page sheet is delivered when an original is recorded from the first page, and the sheets are successively delivered in page order, and therefore the second page recording sheet is delivered on the first page recording sheet. Accordingly, the page order of the recording sheets is disordered, and it takes a long time to finish the sheets so that the sheets are aligned in page order. Accordingly, a recording sheet reversing device is provided by which the sheets are successively delivered with the image facing downward and aligned in page order, by reversing the recording sheet delivered from the image forming apparatus by a reversing means.
As the recording sheet reversing device, Japanese Patent Publication Open to Public Inspection Nos. 267260/1991, 750/1993, 70018/1993, 53252/1996, 85662/1996, 85663/1996, etc., are disclosed.
A guide slot is provided to insert the leading edge of the recording sheet, conveyed by a conveying roller after the recording sheet has been delivered from the image forming apparatus, into a drum-like formed recording sheet reversing means, and the recording sheet reversing means is reversed after the leading edge of the delivered recording sheet has been inserted into the guide slot.
For example, Japanese Patent Publication Open to Public Inspection No. 267260/1991 is structured such that a guide slot is formed on a reversing disk body; the recording sheet is conveyed by a conveying roller pair; and the leading edge of the recording sheet is inserted into the guide slot. When the recording sheet is inserted, the reversing disk body is stopped, however, when the leading edge of the recording sheet is inserted into the narrow guide slot, it can not be smoothly inserted if the leading edge of the recording sheet has any curve or bend.
The guide slot is formed into a long curve along the reversing disk body. In a thin recording sheet, there is a case where, because it has a smaller stiffness, it is bent on the way, and can not be inserted to a predetermined depth. In this case, because the recording sheet is held by the guide slot, the recording sheet is dropped out of the guide slot when the reversing disk body is reversed, and a recording sheet reversing operation can not be smoothly carried out. Specifically, when the reversing operation is carried out at a higher speed, a provability becomes higher in which the recording sheet is dropped out of the guide slot, and the reversing operation can not efficiently be carried out. Reversely, in the case of the thick recording sheet with high stiffness, there is a problem in which it can hardly be inserted into the guide slot.
Further, Japanese Patent Publication Open to Public Inspection No. 53252/1996 is structured such that a long receiving slot is provided to insert the recording sheet into a disk unit which is reversing-operated; and the leading edge of the recording sheet is inserted into the disk unit and the sheet is reversely conveyed. Next, when the disk unit is rotated and a reciprocating boss member is moved to a lower position, it is dropped downward by gravity, and presses the recording sheet in the receiving slot. In this structure also, because the leading edge of the recording sheet is inserted into the long receiving slot, in also the case of the thin recording sheet, in the same manner as described above, the sheet is bent on the way due to the lower stiffness of the recording sheet, or reversely, in the case of the thick recording sheet with higher stiffness, the recording sheet is hardly inserted into the guide slot, which are problems. Further, in the reciprocating boss member to hold the recording sheet in the receiving slot, the recording sheet inserted into the receiving slot of the disk unit is not held when the reciprocating boss member is not moved to the lower position, and during the reverse conveyance, the recording sheet is only inserted simply into the receiving slot, and thereby the recording sheet is easily dropped out of the receiving slot.